Solvent effect on the photocatalytic reduction of 4-nitrophenol in titanium dioxide suspensions

Kinetic and DFT Studies on the Ag/TiO2‐Photocatalyzed Selective Reduction of Nitrobenzene to Aniline

“…[23] Hoffmann et al proposed a mechanism for TiO 2 -photocatalyzed CCl 4 reduction involving direct reduction via the e À cb transfer and indirect reduction the CCH 2 OH radicals. [24] However, in the present system, the direct e À cb reduction seems to be more advantageous than the reduction by CCH 2 OH radicals because the former proceeds on the reduction sites (Ag nanoparticle surfaces) with a high Ph-NO 2 concentration and the opposite is true for the latter [condition (2)]. CH 3 OH and (CH 3 ) 3 COH are known to act as hole-capturing agents to accelerate various TiO 2 photocatalytic reactions, [25,26] where the holes in the valence band (h þ vb ) are captured by CH 3 OH or (CH 3 ) 3 COH to yield CCH 2 OH or CCH 2 (CH 3 ) 2 COH radicals, respectively.…”

“…The reduction of nitrobenzene (Ph-NO 2 ) is an interesting target for TiO 2 photocatalytic reactions, because it is of significance in organic synthesis and may be extended further to NO x treatment. [1] Brezova et al [2] and Ferry et al [3] reported that Ph-NO 2 is selectively reduced to aniline (Ph-NH 2 ) using P-25 (Degussa), which is a mixture of anatase and rutile TiO 2 (70:30 w/w), as a photocatalyst in the presence of CH 3 OH, while the activity strongly depends on the kind of TiO 2 . [4] Ph-NO 2 is commercially reduced with Sn/HCl, which results in a waste-disposal problem.…”

“…[5] Although hydrogen can also be used under high pressure with a transition metal catalyst, the safety issues associated with handling during plant scale production remains a major concern. [6] Recently, the loading of Ag nanoparticles has been found to endow inactive TiO 2 with a very high photocatalytic activity for the selective reduction of Ph-NO 2 to Ph-NH 2 . [4] A deeper understanding of the reason for this effect is necessary to deduce useful and general guidelines for highly active and selective photocatalytic reactions.…”

Study on Photocatalytic Organic Reactions Using Photocatalytic Microreactors

“…9 Although the oxidation ability of photocatalysts is often the focus, they also have reducing ability, which could be controlled by depositing noble metals on the surface 5,10 and the reduction reaction of nitrobenzene has been well studied. [11][12][13][14] If inorganic photocatalysts could be utilized effectively for organic syntheses and conversions, it would be beneficial as 'green chemistry' since they are mostly non-toxic and also easily separated after reactions because they are particulate. Furthermore, a wide variety of new photocatalytic materials with the capability of visible-light reaction have been developed in recent years due to strong demand for light harvesting applications such as solar fuels and solar cells.…”

Surface Properties and Photocatalytic Activity of Ptcore/Agshell Nanoparticle‐Loaded TiO2

“…[14] In contrast, TiO 2 photocatalytic reductions induced by excited electrons with a mild reduction power may be used in the development of a green chemical process that occurs under ambient temperature and pressure without poisonous substances. Two research groups, Brezovµ et al [15] and Ferry et al, [16] have reported the TiO 2 -photocatalyzed reduction of nitrobenzene (NB) to AN using P-25 (Degussa), which is well known to have high photocatalytic activity. More recently, we have found that the reaction is drastically enhanced with the loading of Ag nanoparticles on less active TiO 2 .…”